1. Field of the Invention
The present invention relates to a photo-detection device for recording information on an optical disk and retrieving recorded information in an optical recording/retrieving apparatus such as a CD player, a magneto-optical disk drive, or the like.
2. Related Background Art
Along with recent development of the semiconductor laser diode techniques, a semiconductor laser diode, which is smaller in size than a gas laser, is used as a light source for an optical electronic equipment using coherent light. The semiconductor laser diode is widely used in an optical recording apparatus for recording/retrieving information on/from an optical disk using an optical pickup head.